But someone will say, “You have faith and I have works.” Show me your faith apart from your works, and I will show you my faith by my works.
-James 2:18 ESV
I kinda like that James is a smart-aleck. I don't know if you read it like that, so let me explain.
I imagine he has someone in mind, let's call him Steve, and Steve is always trying to argue with James. So james, knowing this, replies to Steve before he even said anything. He knows what he'll say, so he quotes him, and I imagine he would have said it like this, "But one of you smart guys (Steve) will say to me, 'I have faith and I have works and they work great separately. I don't think faith should ever be involved with work.'"
So, James, being the kind of guy he is immediately replies with, "Oh yeah, smart guy? You show me you believe in something without doing anything and I'll show you what I believe by doing it." James understood that you couldn't truly show others your faith passively. You had to be active. Teaching someone how to run and showing them are two different things. Both may believe that they're teaching correctly, but only one is showing that what they're teaching is actually real, that it's effective, and it has results. The other is full of hot air.
James follows up with this:
You believe that God is one; you do well. Even the demons believe—and shudder!
-James 2:19 ESV
Let me rephrase. "You believe in God, Steve, and that's fine and dandy to say you do. But Even the demons believe in God and are able to talk about Him, but when they do, even they have a physical reaction to Him and shudder in fear!"
Don't be like Steve this week and be a Facebook Christian. Live out your Christianity!